Magnetic writer having multiple gaps with more uniform magnetic fields across the gaps

ABSTRACT

A magnetic device according to one embodiment includes a source of flux and a magnetic yoke coupled to the source of flux. The source of flux includes a thin film coil having multiple turns. The magnetic yoke has a pole with two or more gaps, wherein the coil turns have a non-uniform placement in the magnetic yoke for creating a higher magnetic field at one of the gaps than another of the gaps during writing. A magnetic device according to another embodiment includes a source of flux. A geometry of the magnetic pole near or at one of the gaps is different than a geometry of the magnetic pole near or at another of the gaps to help equalize fields formed at the gaps when the source of flux is generating flux.

BACKGROUND

The present invention relates to data storage systems, and moreparticularly, this invention relates to magnetic write heads havingmultiple gaps.

In magnetic storage systems, data is read from and written onto magneticrecording media utilizing magnetic transducers commonly. Data is writtenon the magnetic recording media by moving a magnetic recordingtransducer to a position over the media where the data is to be stored.The magnetic recording transducer then generates a magnetic field, whichencodes the data into the magnetic media. Data is read from the media bysimilarly positioning the magnetic read transducer and then sensing themagnetic field of the magnetic media. Read and write operations may beindependently synchronized with the movement of the media to ensure thatthe data can be read from and written to the desired location on themedia.

An important and continuing goal in the data storage industry is that ofincreasing the density of data stored on a medium. For tape storagesystems, that goal has led to increasing the track density on recordingtape, and decreasing the thickness of the magnetic tape medium. However,the development of small footprint, higher performance tape drivesystems has created various problems in the design of a tape headassembly for use in such systems.

SUMMARY

A magnetic device according to one embodiment includes a source of fluxand a magnetic yoke coupled to the source of flux. The source of fluxincludes a thin film coil having multiple turns. The magnetic yoke has apole with two or more gaps, wherein the coil turns have a non-uniformplacement in the magnetic yoke for creating a higher magnetic field atone of the gaps than another of the gaps during writing.

A magnetic device according to another embodiment includes a source offlux. A geometry of the magnetic pole near or at one of the gaps isdifferent than a geometry of the magnetic pole near or at another of thegaps to help equalize fields formed at the gaps when the source of fluxis generating flux.

Any of these embodiments may be implemented in a magnetic data storagesystem such as a tape drive system, which may include a magnetic head asrecited above, a drive mechanism for passing a magnetic medium (e.g.,recording tape) over the magnetic head, and a controller electricallycoupled to the magnetic head.

Other aspects and embodiments of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic diagram of a simplified tape drive systemaccording to one embodiment.

FIG. 2 is a partial tape bearing surface view of a head according to oneembodiment.

FIG. 3 is a cross sectional view of FIG. 2 taken along Line 3-3 of FIG.2.

FIG. 4 shows an alternate embodiment having a pancake coil.

FIG. 5 is a cross sectional view of FIG. 2 taken along Line 5-5 of FIG.2.

FIG. 6 is a partial tape bearing surface of a head according to oneembodiment.

FIG. 7 is a partial tape bearing surface of a head according to oneembodiment.

FIG. 8 is a partial tape bearing surface of a head according to oneembodiment.

FIG. 9A is a partial tape bearing surface of a tandem head according toone embodiment.

FIG. 9B is a cross sectional view of FIG. 9A taken along Line 9B-9B ofFIG. 9A.

FIGS. 10A-C illustrate one method for forming a writer.

FIGS. 11A-C illustrate another method for forming a writer.

FIGS. 12A-C illustrate yet another method for forming a writer.

FIG. 13A is a partial tape bearing surface of a head according to oneembodiment.

FIG. 13B is a partial cross-sectional view of FIG. 13A taken along Line13B-13B of FIG. 13A.

FIG. 13C is a partial cross-sectional view a head according to oneembodiment.

FIG. 13D is a partial cross-sectional view a head according to oneembodiment.

FIG. 13E is a partial cross-sectional view a head according to oneembodiment.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified.

The following description discloses several preferred embodiments ofmagnetic systems, as well as operation and/or component parts thereof.Particularly, disclosed are structures that minimize gap to gap fieldvariations that otherwise would occur in magnetic devices havingmultiple gaps. While the teachings herein may apply to magnetic devicessuch as inductors, switches, and magnetic engines of various types, muchof the following description is presented in terms of a magneticrecording head. This has been done by way of nonlimiting example onlyand to aid the reader by placing embodiments of the present invention ina context.

In one general embodiment, a magnetic device includes a source of flux;a magnetic pole coupled to the source of flux, the magnetic pole havingtwo or more gaps; and a low reluctance path positioned towards at leastone of the gaps and not positioned towards at least one other of thegaps for affecting a magnetic field formed at the at least one of thegaps when the source of flux is generating flux.

In another general embodiment, a magnetic device includes a source offlux comprising a coil having multiple turns; and a magnetic yokecoupled to the source of flux, the magnetic yoke having a pole with twoor more gaps, wherein the coil turns have a non-uniform placement in themagnetic yoke for altering a magnetic field formed at the at least oneof the gaps during writing.

In yet another general embodiment, a magnetic device includes a sourceof flux; and a magnetic pole coupled to the source of flux, the magneticpole having two or more gaps. A geometry of the magnetic pole near or atone of the gaps is different than a geometry of the magnetic pole nearor at another of the gaps to help equalize fields formed at the gapswhen the source of flux is generating flux.

FIG. 1 illustrates a simplified tape drive 100 of a tape-based datastorage system, which may be employed in the context of the presentinvention. While one specific implementation of a tape drive is shown inFIG. 1, it should be noted that the embodiments described herein may beimplemented in the context of any type of tape drive system.

As shown, a tape supply cartridge 120 and a take-up reel 121 areprovided to support a tape 122. One or more of the reels may form partof a removable cassette and are not necessarily part of the system 100.The tape drive, such as that illustrated in FIG. 1, may further includedrive motor(s) to drive the tape supply cartridge 120 and the take-upreel 121 to move the tape 122 over a tape head 126 of any type.

Guides 125 guide the tape 122 across the tape head 126. Such tape head126 is in turn coupled to a controller assembly 128 via a cable 130. Thecontroller 128 typically controls head functions such as servofollowing, writing, reading, etc. The cable 130 may include read/writecircuits to transmit data to the head 126 to be recorded on the tape 122and to receive data read by the head 126 from the tape 122. An actuator132 controls position of the head 126 relative to the tape 122.

An interface may also be provided for communication between the tapedrive and a host (integral or external) to send and receive the data andfor controlling the operation of the tape drive and communicating thestatus of the tape drive to the host, all as will be understood by thoseof skill in the art.

The readers and writers in the head 126 may be arranged in a piggybackconfiguration. The readers and writers may also be arranged in aninterleaved configuration. Alternatively, each array of channels may bereaders or writers only. Other configurations are also possible. Any ofthese arrays may contain one or more servo readers.

Some embodiments are constructed to operate with the magnetic mediumrunning along the plane of the wafer. These heads are typically referredto as “planar” heads. Other embodiments are constructed to operate withthe magnetic medium running orthogonal to a plane of deposition of itsconstituent layers.

FIG. 2 illustrates a head 300 according to one embodiment. FIG. 3 showsa cross section of FIG. 2 taken along Line 3-3. FIG. 5 shows a crosssection of FIG. 2 taken along Line 5-5. As shown in FIGS. 3-5, the head300 has a top pole 305 with a first write gap 302 therein. The top poleis positioned above a plane extending through the bottom pole 303 andparallel to a plane of deposition of the bottom pole. Side poles 310connect the top and bottom poles. As best seen in FIG. 5, the top poleis at least partially offset from the bottom pole in a directionparallel to a plane of deposition of the top pole. In one approach, aportion of the top pole does not overlie the bottom pole. In anotherapproach, parallel, central longitudinal axes of the top and bottompoles are offset from one another in a direction parallel to a plane ofdeposition of the top pole.

The top pole may partially or fully overlie the bottom pole. In otherembodiments, the top pole is completely offset from the bottom pole suchthat the top pole does not overlie the bottom pole. See, e.g., FIG. 5.

The top pole may be constructed of a high moment material such as NiFealloys, including 45/55 NiFe, or other high moment materials.Illustrative thicknesses of the top pole are between about 0.5 micronsand about 3 microns, but could be higher or lower. The top pole may betapered or shaped as in FIG. 3, 11C, etc. to focus the flux at the gap.

The bottom pole and side poles can be a high permeability material suchas permalloy, CZT, etc. The bottom pole may have a lower magnetic momentthan the top pole, in which case it would be preferably made widerand/or thicker than the top pole. The same applies to the side poles.The amount of open space created by the offset between the top andbottom poles may be tailored to maximize the head efficiency.

A source of flux such as a first coil 306 generates a magnetic fluxacross the first write gap, thereby causing a magnetic flux to emanatefrom the first gap 302.

The first coil may be a helical coil or a pancake coil, the helical coilbeing shown in FIGS. 2 and 10B, and the pancake coil being shown in FIG.4. As also shown in FIG. 10C, the top pole does not overlie the firstcoil in some embodiments, but may overlie portions of the coil in otherembodiments, e.g., one having a pancake coil. Note that in someembodiments, the source of flux may include multiple coils, includingcoils that operate simultaneously as well as those that areindependently addressable.

Multiple write gaps are preferably present in some embodiments.Referring to FIG. 6, a second write gap 602 may be present in the toppole, the first coil also generating a magnetic flux across the secondwrite gap. FIG. 7 depicts an embodiment in which first, second and thirdwrite gaps 302, 602, 702 are present in the top pole, the first coilgenerating a magnetic flux across the first, second and third writegaps. FIG. 8 depicts an embodiment in which first, second, third andfourth write gaps 302, 602, 702, 704 are present in the top pole, thefirst coil generating a magnetic flux across the first, second and thirdwrite gaps.

The write gaps may be oriented at any angle relative to each other. Forexample, the first and second write gaps may be oriented at an anglerelative to each other selected from a range of 0 degrees to less than180 degrees.

In another illustrative approach, the first write gap is oriented at anangle of about 2 to about 90, inclusive, relative to the direction ofmedia travel thereover, while the second write gap may also be orientedat an angle of about 2 to about 90 (which is intended to encompassbetween about −2 and about −90 degrees) relative to the direction ofmedia travel thereover. While such heads may be used for any type ofrecording, including data recording, such heads are especially usefulfor writing servo patterns to a magnetic medium such as a tape.

In other embodiments, the gaps may be oriented for writing data, such asconventional or azimuthal data recording. In one approach, some of thewrite gaps may be oriented about parallel to each other and may be usedfor DC erasing tape.

As also shown in FIG. 6, wing portions 504 may be added to this andother embodiments to reduce the possibility of saturation at the ends ofthe gaps. Preferably, the angles α of the wing portion and centralregion 502 of the top pole 305 relative to an imaginary line coaxialextending along the gap are about the same.

The gaps in this or any other embodiment do not need to extend to theends of the pole. Rather, the gaps may be positioned in the face of thetop pole. Optional bulbous ends on the gaps improve the uniformity ofthe flux along the gap, as shown in FIG. 7.

Moreover, in some approaches, centers of the gaps may generally liealong a line oriented parallel to a direction of tape travelthereacross, e.g., are centered on the line. However, in otherembodiments, the write gaps have offset centers relative to thedirection of tape travel thereacross.

In some embodiments, the first and second write gaps may have about asame track width. In further embodiments, the first and second writegaps have different track widths.

Note also that the gaps need not be centrally located on a given poleregion. Rather, it may be desirable for asymmetric placement of a gap insome embodiments.

Several illustrative multi-gap configurations are presented in U.S.patent application Ser. No. 12/141,375 to Biskeborn et al., having title“Tandem Magnetic Writer,” filed Jun. 18, 2008, and which is hereinincorporated by reference.

In magnetic recording applications such as servo writing, a multiple gaprecording head may be used to produce an application specific magneticpattern. However, when multiple gaps are placed into a magnetic yoke,the resulting deep gap fields exhibit a gap to gap variation in theirintensity. This intensity variation ultimately leads to gap to gapvariations in the recorded patterns and thus a reduction in the qualityof the recorded pattern. Accordingly, in some embodiments, features arepresent in the head that make the gap to gap field intensity moreuniform. In some approaches, some or all of the gaps in a head aredesigned to increase the field intensity in the selected gaps, such asby having different throat heights. In other approaches, a parallelreluctance path is provided to allow some flux to circumvent the gap. Infurther approaches, the placement of the coils in the magnetic yoke isset. Combinations of such approaches may also be used. Thus, variousdesigns may include either introducing or removing material at or nearthe gaps. Note that the approaches presented herein to equalize the gapto gap field variations may be used with any multi-gap head design.

Presented by way of example only, several embodiments applied to a threegap head 1300, as illustratively shown in FIG. 13A, and selected fortheir manufacturability in a planar head design, are shown in FIGS.13B-13E, each of which represents a cross sectional view of the head1300 of FIG. 13A as viewed along plane 13B-13B. The thick arrowsrepresent a general direction of the flow of flux around or across agap.

Referring first to FIG. 13A, there is shown a head 1300 having threegaps 1302, 1304, 1306. One approach to make the field intensity moreuniform across the gaps includes placing a low reluctance path, e.g.,made of a ferromagnetic material, near one or more of the gaps foraffecting a magnetic field formed at the at least one of the gaps whenthe source of flux is generating flux. The low reluctance paths have theeffect of shunting some of the flux away from the adjacent gap, andshunting that flux to the next portion of the top pole. The net resultis that the field formed at the adjacent gap is reduced. Preferably, thelow reluctance path equalizes the magnetic field formed at the gap(s)closest thereto with a magnetic field formed at another of the gaps sothat the magnetic fields are substantially equivalent, e.g., have verysimilar writing characteristics.

Referring to FIG. 13B, low reluctance paths 1310, 1312 are positionednear the outer gaps 1302, 1306. In this approach, the low reluctancepaths 1310, 1312 are magnetic shunts located proximate to the gaps butnot magnetically connected to the top pole. The low reluctance paths1310, 1312 have the effect of shunting some of the flux away from theadjacent gap 1302, 1306, and shunting that flux to the next portion ofthe top pole. The net result is that the field formed at the adjacentgap is reduced. In the embodiment shown in FIG. 13B, this has the effectof equalizing the fields formed at the three gaps. Without the shunts,the middle gap 1304 would tend to exhibit less field than the outer gaps1302, 1306. The low reluctance paths 1310, 1312 may be formed as anadditional layer in the structure using known techniques such asplating, sputtering, plasma vapor deposition, etc. Note that thedimensions of the low reluctance paths 1310, 1312 may be selected basedon modeling of the resultant structure, as will be understood by oneskilled in the art.

Referring to FIG. 13C, low reluctance paths 1314, 1316 are againpositioned near the outer gaps 1302, 1306. However, in this approach,the low reluctance paths 1314, 1316 are magnetic shunts locatedproximate to the gaps and which are magnetically connected to the toppole. For example, the low reluctance paths may be formed from the seedlayer that was used when electrodepositing the top pole. The lowreluctance paths 1314, 1316 have the effect of allowing flux tocircumvent the adjacent gap 1302, 1306. The net result is that the fieldformed at the adjacent gap is reduced. In the embodiment shown in FIG.13C, this has the effect of equalizing the fields formed at the threegaps. Without the shunts, the middle gap 1304 would tend to exhibit lessfield than the outer gaps 1302, 1306. The low reluctance paths 1314,1316 may be formed as an additional layer in the structure using knowntechniques such as plating, sputtering, plasma vapor deposition, etc.Note that the dimensions of the low reluctance paths 1314, 1316 may beselected based on modeling of the resultant structure, as will beunderstood by one skilled in the art.

In yet another embodiment, a geometry of the magnetic top pole near orat one of the gaps may be different than a geometry of the magnetic polenear or at another of the gaps to equalize fields formed at the gapswhen the source of flux is generating flux. In one approach, thegeometry of the magnetic pole includes at least two of the gaps havingdifferent throat heights. For example, as shown in FIG. 13D, the throatheight of the middle gap 1304 is smaller than the throat heights of theouter gaps 1302, 1306. This has the effect of increasing the fluxdensity near the tape bearing surface at the middle gap 1304. Thereduced throat height may be defined by a stepped geometry as shown, orother approach.

In another embodiment, the width of one or more of the gaps may bedifferent than the width of the other gap(s). This has the effect ofvarying the flux density at the various gaps. By appropriate adjustmentof the gap widths, the fields at the various gaps can be adjusted.

In another embodiment, the geometry of the magnetic pole includes a sideportion of the pole being close to the one of the gaps for effectivelyadding a parallel flux path. As shown in FIG. 13E, the side walls of thehead may be positioned closer to the outer gaps 1302, 1306 to allow someflux to bypass the gaps.

In a further embodiment, a magnetic device includes a source of fluxcomprising a coil having multiple turns, and a magnetic yoke coupled tothe source of flux. The magnetic yoke may be similar to that shown inFIG. 2, with the bottom portion being offset from the top pole. In analternate embodiment, the magnetic yoke may be aligned vertically. Otherdesigns may also be used. The magnetic yoke may have a top pole with twoor more gaps, where the coil turns have a non-uniform placement in themagnetic yoke for altering a magnetic field formed at the at least oneof the gaps during writing. An illustrative embodiment is shown in FIG.4. The field in a gap depends on the position of the turns of the coil350. By positioning the coil turns in the yoke to be about the same foreach gap, the fields formed at each gap will be about equivalent. Incontrast, if the coil turns in the yoke were positioned more towards oneof the gaps than the other or more towards one side pole or the other,the former gap would exhibit a higher field.

In one embodiment, a head includes two or more independently addressablewrite gaps, where the gaps preferably lie along a line oriented parallelto a direction of tape travel thereacross, i.e., having at leastportions thereof aligned in a direction parallel to a direction of mediatravel thereover. While such heads may be used for any type ofrecording, including data recording, the heads are especially useful forwriting servo patterns to a magnetic medium such as a tape.

In one embodiment, a multi-gap head is part of a plurality of headsdesigned to work together such as in a tandem head. FIG. 9A illustratesa simple tandem head 800 according to one embodiment. Though each headhas only a single gap, it should be understood that each head may havemultiple gaps. FIG. 9B is a cross sectional view of FIG. 9A taken alongLine 9B-9B of FIG. 9A. As shown, the tandem head has top poles 305 withfirst and second write gaps 302, 304 therein, and independentlyaddressable first and second coils. The first coil is operative to causea magnetic flux to emanate from the first gap 302. The second coil isoperative to cause a magnetic flux to emanate from gap 304.

The write gaps 302, 304 in this and other embodiments may beconcurrently formed. This has the advantage of allowing precisealignment of the write gaps. Also, the various regions of the pole 305may be concurrently formed in this and other embodiments.

More information about tandem head configurations and operation ispresented in U.S. patent application Ser. No. 12/141,375 to Biskeborn etal., having title “Tandem Magnetic Writer,” filed Jun. 18, 2008, andwhich has been incorporated by reference.

Magnetic tape uses a written servo pattern to indicate the lateralposition on tape. This servo pattern is used to indicate the lateralposition, on tape, of the various written tracks. The servo pattern isnot perfect due to variations in tape velocity and lateral tape motionin the servo writer system during servo writing. The component of theservo pattern due to the velocity variations and lateral motion istermed the ‘written in’ component and interferes with capabilities ofthe track following actuator in the drive. For example, components ofthe ‘written in’ servo can be incorrectly interpreted by the trackfollowing actuator as lateral positioning error and so cause the head tomove in response thus resulting in mistracking. Greater trackfollowingaccuracy becomes more important as written tracks get narrower. Hence‘written in’ servo noise limits the ultimate track pitch attainable inmagnetic tape recording.

In use, some of the embodiments described herein may be used as a servowriter using methods such as those described in U.S. patent applicationSer. No. 12/141,363 to Biskeborn et al., having title “Systems andMethods for Writing Servo Patterns,” filed Jun. 18, 2008, and which isherein incorporated by reference.

FIGS. 10A-C illustrate one general method for forming a writer.Conventional processing may be used to form the various parts. Moreover,additional layers such as insulating layers, masks, etc. may be addedand/or removed. Note that some underlying layers are shown in shadow inFIGS. 10B and 10C.

Referring to FIG. 10A, a bottom pole 303 and at least portions of thefirst coil 306 are formed above any conventional substrate. The coil ispreferably electrically isolated from the bottom pole. Preferably, afirst magnetic field is applied during formation of the bottom pole. Thefirst magnetic field is preferably oriented about perpendicular to along axis 1002 of the bottom pole. This tends to orient the magneticdomains in the direction of the applied magnetic field, which isorthogonal to the long axis, thereby improving switching speed bycausing rotation of domain magnetization rather than motion of domainwalls, which is a slower process. Note that the long axis of a componentlies generally along a primary path of magnetic flux as it travelsthrough the component.

Referring to FIG. 10B, side poles 310 are formed. The coil 306 is alsocompleted. The side poles provide the flux path between the top andbottom poles in the completed device. Preferably, a second magneticfield is applied during formation of the side poles. The second magneticfield is preferably oriented about perpendicular to a long axis 1004 ofone or both side poles.

Referring to FIG. 10C, a top pole 305 is formed above a plane extendingthrough the bottom pole and parallel to a plane of deposition of thebottom pole, where the top pole is at least partially offset from thebottom pole in a direction parallel to a plane of deposition of the toppole. Preferably, a third magnetic field is applied during formation ofthe top pole. The first magnetic field is preferably oriented aboutperpendicular to a long axis 1006 of the top pole. The longitudinal axesof the top and bottom poles are preferably oriented about parallel toeach other, but need not be. Also, the longitudinal axes of the sidepoles are preferably not parallel to the long axis of the top pole, butcould be.

As shown in FIG. 10C, at least one write gap 302 is formed in the toppole. FIGS. 11A-C and 12A-C illustrates different methods to form writegaps. Of course, any other suitable method may be used.

FIGS. 11A-C illustrate one method for forming a writer havingindependently addressable write gaps. Conventional processing may beused to form the various parts. Referring to FIG. 11A, first and secondwrite coils 306, 308 are formed. First and second write gaps 302, 304are also formed. Referring to FIG. 11B, material is deposited forconcurrently forming write pole regions 1202, which may or may not bedefined at this point. Referring to FIG. 11C, the structure isplanarized.

FIGS. 12A-C illustrate another method for forming a writer. Again,processing may be used to form the various parts. Referring to FIG. 12A,first and second write coils 306, 308 are formed. Write pole regions1402 are also formed. Write gap material 1404 is formed over the writepole regions, as shown in FIG. 12B. Further processing may be performedprior to formation of a common write pole region 1406 adjacent first andsecond write gaps 302, 304, as shown in FIG. 12C.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of a preferred embodiment shouldnot be limited by any of the above-described exemplary embodiments, butshould be defined only in accordance with the following claims and theirequivalents.

What is claimed is:
 1. A magnetic device, comprising: a source of fluxcomprising a thin film coil having multiple turns; and a magnetic yokecoupled to the source of flux, the magnetic yoke having a pole with twoor more gaps, wherein the gaps are positioned and configured to eachwrite an individual transition to a magnetic medium upon energization ofthe coil.
 2. A device as recited in claim 1, wherein the device isconstructed to operate with a magnetic medium running parallel to aplane of deposition of the magnetic yoke.
 3. A device as recited inclaim 1, wherein the gaps are configured to write servo patterns on amagnetic medium.
 4. A device as recited in claim 3, wherein the coilturns have a non-uniform placement in the magnetic yoke for creating ahigher magnetic field at one of the gaps than another of the gaps duringwriting.
 5. A device as recited in claim 1, wherein a geometry of themagnetic yoke near or at one of the gaps is different than a geometry ofthe magnetic yoke near or at another of the gaps to help equalize fieldsformed at the gaps when the source of flux is generating flux.
 6. Adevice as recited in claim 1, wherein the coil turns are positioned moretowards one of the gaps than another of the gaps.
 7. A magnetic device,comprising: a source of flux; and a magnetic pole coupled to the sourceof flux, the magnetic pole having two or more gaps, wherein a geometryof the magnetic pole near or at one of the gaps is different than ageometry of the magnetic pole near or at another of the gaps to helpequalize fields formed at the gaps when the source of flux is generatingflux, wherein the gaps are positioned and configured to each write anindividual transition to a magnetic medium upon energization of thesource of flux.
 8. A device as recited in claim 7, wherein the geometryof the magnetic pole includes a side portion of the magnetic pole beingclose to the one of the gaps for effectively adding a parallel fluxpath.
 9. A device as recited in claim 7, wherein the geometry of themagnetic pole includes at least two of the gaps having different throatheights.
 10. A device as recited in claim 7, wherein at least one of thegaps has a stepped geometry.
 11. A device as recited in claim 7, whereinthe device is constructed to operate with the magnetic medium runningalong the plane of deposition of the magnetic pole.
 12. A device asrecited in claim 7, wherein the device is constructed to operate withthe magnetic medium running orthogonal to a plane of deposition of themagnetic pole.
 13. A device as recited in claim 7, wherein the gaps areconfigured to write servo patterns on a magnetic medium.
 14. A device asrecited in claim 7, wherein the geometry equalizes magnetic fieldsformed at one of the gaps with a magnetic field formed at another of thegaps so that the magnetic fields are substantially equivalent.
 15. Adevice as recited in claim 7, wherein the source of flux comprises athin film coil having multiple turns.